Grinder with wheel dresser



N 1961 T. J. LINDEM ET AL 3,009,294

GRINDER WITH WHEEL DRESSER Filed March 7, 1960 5 Sheets-Sheet 1 mu TLomcL-J Q1 Lpnciern,

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GRINDER WITH WHEEL DRESSER 3 Sheets-Sheet 5 L Filed March 7, 1960 k xo. J L indem QR van YQ o em 15. wO-I W, dd 16M United States Patent 3,009,294 GRINDER WITH WHEEL DRESSER Thomas J. Lindem and Jan van Roojen, Rockford, Ill.,

assignors to The Ingersoll Milling Machine Co., Rockford, Ill., a corporation of Illinois Filed Mar. 7, 1960, Ser. No. 13,338 4 Claims. (Cl. 51-100) This invention relates to power operated grinders of the type commonly used for sharpening multiple blade cutters and having a rotary abrasive wheel reciprocated back and forth across the work to be finished and also across a dressing tool to maintain the desired contour and position of the active surface of the wheel. More particularly, the invention relates to a grinder having a mechanism for modifying the speed of the grinding wheel automatically to compensate for the reduction in diameter resulting from the intermittently dressing of the wheel whereby to maintain a substantially constant peripheral speed of the wheel in spite of the changes in its diameter.

The general object is to effect the automatic speed adjustment of the grinding Wheel within a simple V-belt drive connection between the wheel and its driving shaft.

A more detailed object is to utilize the motion of feeding the grinding wheel step by step toward the dressing tool to automatically change the effective diameter of the driven belt pulley and thereby maintain the peripheral speed of the grinding wheel substantially constant at all times.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which FIGURE 1 is a side elevational view of a cutter grinder embodying the novel features of the present invention.

FIG. 2 is a fragmentary section taken along the line 22 of FIG. 1.

FIG. 3 is a fragmentary section taken along the line 33 of FIG. 2.

FIG. 4 is a view of part of FIG. 3 showing a different position of the parts.

FIG. 5 is a fragmentary front elevational view.

FIGS. 6 and 7 are fragmentary views showing the variations in the shape of the driving belt for different sizes of the grinding wheel.

For purposes of illustration the invention is shown in the drawings incorporated in a machine for reciprocating a rotary abrasive disk 10 back and forth along a generally horizontal path to move the lower side of the wheel periphery along radially extending cutting edges 11 of a multiple blade milling cutter 12 and also across the tip 13 of a diamond point type of tool by which the wheel peripheral is dressed away intermittently and held at the desired contour. The cutter is mounted adjustably on a support 14 with the blade edges facing upwardly and is adapted to be indexed step by step about an upright axis 15 to bring the successive blade edges into the path of the grinding wheel. The dressing tool is disposed adjacent but spaced outwardly from the periphery of the cutter to be sharpened and projects upwardly from the end of an arm 16 rigid with a slide 17 which is mounted on the machine base 18.

The grinding wheel 10 which takes the form of a relatively thin disk of bonded abrasive is clamped as shown in FIG. 3 to the forward end of a horizontal shaft 19 projecting from and journaled in bearings 20 in a head 21 which includes a guard 21 enclosing the upper part of the wheel. The head is slidably guided along parallel rods 22 extending vertically between and supported by spaced lugs 23, 2'4 projecting forwardly from a carriage 25. Wings 26 projecting laterally from Patented Nov. 21, 1961 the carriage are clamped to parallel rods 27 which are slidable in guide bushings 28 supported by a housing 29 having oppositely projecting trunions 30 journaled in lugs 31 laterally spaced across and upstanding from the top of the table 17. The entire wheel assembly is thus adapted to rock vertically about a fulcrum 32 to carry the grinding disk up and down. At the same time, the wheel head 21 is adapted to slide up and down along the guide rods 22 to enable the wheel to 'be fed into the dressing tool and the wheel periphery thus reduced in size to traverse the desired path across the cutting edge 11 then in position to be sharpened.

Rocking of the wheel assembly up and down as it passes across the dressing point and along the blade edge 11 to follow the contour of the latter is effected by a cam 34 attached to the bottom of the carriage 25 and riding on a follower 35 upstanding from the table 17. As thecarriage advances from the retracted position of the wheel shown in FIG. 1, the wheel 10 first comes into contact with the dressing point and then follows along the cutter edge 11 to be sharpened. The sharpening and dressing action is repeated on the return stroke of the wheel carriage.

Reciprocation of the carriage is effected in the presentinstance by a hydraulic actuator (FIGS. 1 and 2) including a piston 37 slidable in a cylinder 38 which ismounted in and secured to the housing 29. The forward end of the piston. rod is attached at 39 to the rear end of the carriage 25. 1

Provision is made for feeding the head 21 step by step and downwardly along the guide rods 22 to advance the wheel to the diamond point 13 and enable the wheel periphery to be dressed off intermittently and thus maintained of the proper contour and in the proper plane for sharpening the edges 11 of the cutter blades indexed successively to operating position.- The downward feed may be effected manually by turning a hand crank 41 fast on the outer end of a shaft 42 journaled in the upper part of the head 21 and bevel gear connected at its inner end with a vertical shaft 43 to a screw threaded into a nut 44 journaled in bearings 45 on a casing 46 forming. part of the carriage 25. Between the bearings the nut carries a worm wheel 37 which meshes with a worm 48 on a shaft 49 journaled in the casing.

By turning the shaft 49, the nut may be advanced along the screw 43 thus providing a second way for feeding the wheel head downwardly. For this purpose, suitable power actuated mechanism (not shown) may be provided for effecting such feeding of the wheel head step by step and in synchronism with an automatic cycle of the grinder. During such feeding the screw shaft 43 is held frictionally against turning as by a screw 42 ad-" vanced inwardly against the shaft by turning itshead 42 The increment of feed for the successive blade sharpening cycles is usually less than .0005 of an inch. With the machine thus automated, manual feeding of the wheel head by turning the crank is used mainly in setting up the machine. 'Back lash in the screw connection is taken up by a constant torque spring 51 mountedon the wheel: head 21 with itsfree end 52 secured to the nut casing 46. p

In accordance with the present invention, the wheel shaft 19 is driven through the medium of an endless belt 54 of V cross section disposed in a plane paralleling the path of feed of the wheel '10- and engaging an axially err-- pansible sheave 55' of well known construction whose effective diameter is changed automatically to increase the- ICC ' speed of the wheel to correspond closely to the change scoped hubs 56 57 spline coupled together and to the rear end 19 of the wheel shaft '19. A lever 70 movable about a fixed fulcrum 71 intermediate its ends is coupled at opposite ends 72, 73 to the inner and outer hubs so that the cones are movable toward and away from each other in unison. As a result, the V-groove formed by the conical surface of the disks always remains in a fixed axial plane. A spring 58 is coiled about the hub 57 and acts in compression against an abutment 59 to urge the disks toward each other and thus collapse the pulley to an effective diameter limited by the tensioning of the belt. Of course, the cone angles and the stress in the spring are such as to render the pulley accurately responsive to changes in the belt tension. By manipulating a nut 60, the position of the abutment 59 along the shaft may be adjusted to produce the desired belt tension.

At its upper end, the belt 54 runs around and is seated in the correspondingly shaped V-groove of a pulley 62 having an effective diameter which remains fixed and rotatable in the plane of the collapsible pulley. To this end, the coned disks forming the pulley are fixed to the shaft 64 of an electric motor 65 whose casing is bolted onto the rear side of the carriage 25 at the upper end of the latter. As shown in FIGS. 6 and 7, the vertical space between the dressing point 13 and the axis of the fixed diameter pulley 62 remains constant in all positions of vertical adjustment of the wheel head 21.

' With the arrangement above described, it will be apparent that when the wheel 10 is new and of maximum diameter as shown in FIGS. 3 and 6, it will contact the dressing point 13 and the cutting edge 11 in the intended manner when the head 21 is retracted upwardly and disposed in the upper part of its feed range. At this time and in order to stretch the belt to the tension determined by the stress of the spring 58, the disks 56, 57 will be disposed close together and the belt will engage the outer parts of the coned surfaces. With the pulley 55 of this maximum diameter (see FIGS. 3 and 6) and larger than the drive pulley 62, the wheel 10 will be rotated by the motor at a reduced or minimum speed. This speed is, of course, determined by the sizes of the pulleys 55, 62, the length of the belt, and the tension produced by the spring 58, these 'factors being correlated properly with the motor speed and the initial diameter of the wheel 10 so as to turn the latter at the desired peripheral speed.

At the same time, the angle included between the coned surfaces of the pulley disks 56, 57 is such that as to allow a reduction in the effective diameter of the driven pulley corresponding closely with the reduction in the diameter of the wheel periphery incident to each dressing operation. Thus, as the head 21 is fed downwardly and the wheel is worn away in the successive dressing operations, the wheel shaft 19 is moved away from the pulley 62 and the tension in the belt 49 thus increased correspondingly. This overcomes the stress of the spring 58 which yields to allow the belt to be drawn deeper into the groove of the pulley 55. In each increment of wheel feed, the reduction in the effective diameter of the driven pulley is just enough to compensate for the reduced diameter of the wheel.

When the wheel is substantially used up as shown in FIGS. 4 and 7, the pulley 55 will be expanded fully and the belt will be drawn in close to the shaft 19 and the effective diameter of the pulley will be at a minimum. The drive ratio of the belt transmission is thus increased and the wheel is turned at maximum speed but at substantially the same peripheral speed as when the driven pulley is of maximum diameter as shown in FIG. 3. The overall result therefore is to adjust the drive ratio of the belt transmission automatically and accurately in accordance with the size of the grinding wheel as it is dressed away in service use and as a consequence to maintain the peripheral speed of the wheel substantially constant at all times. Optimum efiiciency of the grinder is thus achieved.

We claim as our invention:

1. In a grinder, the combination of, a support reciprocated back and forth along a predetermined path, a shaft journaled on said support to turn about an axis extending along said path, a disk grinding wheel fast on said shaft, a tool for dressing the periphery of said wheel, means supporting a workpiece to be ground and said dressing tool in spaced relation along said path and for engagement successively by said wheel in opposite end portions of the stroke of said support, a power driven shaft rotatable about a fixed axis, means mounting said support for bodily adjustment transaxially of said first shaft and toward said tool for dressing off an increment of the wheel periphery during reciprocation of said support, a pulley fast on said second shaft and having a V-groove of fixed diameter, a second pulley fast on said first shaft and having a V-groove of variable diameter, an endless V-belt seated and running in the groova of said pulleys, and spring means tending to collapse said second pulley axially and maintain said belt under a substantially uniform tension in the different positions of adjustment of said support.

2. In a grinder, the combination of, a support reciprocated back and forth along a predetermined path, a head mounted on said support for adjustment transversely of said path, a shaft journaled on said head to turn about an axis extending along said path, a disk grinding wheel fast on said shaft, a tool for dressing the periphery of said wheel, means supporting a workpiece to be ground and said dressing tool in spaced relation along said path and for engagement successively by said wheel during the stroke of said support, a power driven shaft mounted on said support to turn about a fixed axis, a pulley fast on said second shaft and having a V-groove of fixed diameter, a second pulley fast on said first shaft and having a V- groove of variable diameter, an endless V-belt stretched between and running in the grooves of said pulleys, and spring means tending to collapse said second pulley and maintain said belt taut and thereby reduce the effective diameter of the pulley as the periphery of said wheel is worn away.

3. In a grinder, the combination of, a support reciprocated back and forth along a predetermined path, a shaft journaled on said support to turn about an axis extending along said path, a disk grinding wheel fast on said shaft, means supporting a workpiece to be ground for engagement by said wheel in the strokes of said support, a power driven shaft rotatable about a fixed axis, means mounting said support for bodily adjustment transaxially of said first shaft and toward said workpiece, a pulley fast on said second shaft and having a V-groove of fixed diameter, a second pulley fast on said first shaft and having a V-groove of variable diameter, an endless V-belt stretched between and running in the grooves of said pulleys, and yieldable means tending to collapse said second pulley and maintain said belt taut.

4. In a grinder, the combination of, a support, a shaft journaled on said support, a disk grinding wheel fast on said shaft, a tool for dressing the periphery of said wheel, means mounting said support and said tool for step by step movement toward each other for dressing said wheel periphery and thereby decrease the wheel diameter, a power driven shaft rotatable about a fixed axis, a pulley fast on said second shaft and having a V-groove of fixed diameter, a second pulley fast on said first shaft and having a V-groove of variable diameter, an endless V-belt seated and running in the grooves of said pulleys, and yieldable means tending to collapse said second pulley to maintain said belt taut and thereby decrease the effective diameter of the pulley as the periphery of said wheel is dressed away.

Oliver Sept. 22, 1936 Silven et a1. Apr. 13, 1954 

